<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>border</title>
  <style>
    .c1 {
      width: 300px;
      height: 150px;
      /* border: 1px solid red; */
      /* border:5px solid red; */
      /* border:5px dotted red; */
      border:5px dashed red;
    }
    .c2 {
      width: 300px;
      height: 150px;
      /* border-width: 30px; */
      border:30px solid transparent;
      border-image:url(./border.png) 30 round;
    }
    .c3 {
      width: 300px;
      height: 150px;
      border-bottom:30px solid red;
      /* border-right:30px solid blue; */
      border-left:30px solid transparent;
      border-right:30px solid transparent;
    }
  </style>
</head>
<body>
  <div class="c1">
  </div>
  <div class="c2">
  </div>
  <div class="c3">
  </div>
</body>
</html>
